Shunt wire

[Nacho-RT74]

where to find a shunt wire for the remote ammeters readings sytems?

Where they available as replacement?

Is there some way to identify it measuring the resistance if they missed the label?

Or... how to set a correct shunt ( wire or plate ) for an ammeter of these?

 

[PurpleBeeper]

Please explain a little more what you mean. What are you trying to do? Do you have a second wire from the alternator main post to the + of the battery and want your ammeter to read correctly? I'd like to know that myself. Are you replacing a fusible link?

 

[Nacho-RT74]

No... let's see, 2 reason for this question.

---a friend of mine is trying to rebuild a 77 Monaco which uses the shunted ammeter system. Electric system is a complete mess on his car

---I have allways played with the idea of become my 74 Charger on a shunted ammeter system. I have a NOS ammeter from 78/79 Lebaron which is the same size ( just would need a face change and related mods ) and incorporates also a low voltage led indicator. BUT I don't have the shunt for this

 

[440+6]

Remote shunt is a great idea, factory should have done it this way.
I am interested on how this works out.
Would the shunt be on the positive or negitive side of the battery?

 

[Nacho-RT74]

Factory did it since 75/76.

A straight wire between alt and batt post with the shunt in the middle and the ammeter wires at a sides of the shunt, allong with the splice from the alt side of the shunt to inside the cab ( allong with sone other splices according with the car equipment )

Allways positive post. Negative is Chassis ground.

 

[440+6]

Reason I asked is because I had a boat and the shunt was on the negitive side.

 

[Pops1967GTX]

 

[Nacho-RT74]

Yeah well, how to know the mopar shunted ammeter specs, and where to find a shunt wire meeting those specs?

 

[RJRENTON]

When switching to a shunt ammeter system, know the calibration of the shunt is critical. The shunt produces a millivoltage voltage drop at given amperage flowing through it. The ammerter measures the millivoltage drop on a calibrated scale in AMPS. it is measuring Voltage not amperage. Example: 50 amps flowing through the calibrated shunt produces a MILLIVOLTAGE of 10 mollivolts. The calibrated scale of the connected meter at 10 millivolts will read 50 amps. Of course, smaller amperage flows through the shunt will produce proportionly less millivoltage and a lower meter reading. The shunt is not directional sensitive and will produce a proportional millivoltage with current flowing in either direction. The indicating meter would need to be a zero center device, to be able indicate current in either direction. This concept works for DC only. AC current is measured differently.
Bob Renton

 

[Nacho-RT74]

This is an specific shunted ammeter, from Lebaron. Thinking on this because is the same size, stud width and gauge deepness then the 71/74 Rallye cluster, and needle toward down like the clock/tach cluster kind. Aside the extra led for low voltage indicator. Just would need to work on the faces change what shouldn't be hard.

 

[Nacho-RT74]

Amplifier coil with the printed circuit board for the voltage led feature

 

[RJRENTON]

Nacho,
I'm not familiar with the instrument you show in the second pix, but it APPEARS that its not a true ammeter with a shunt but an adaptation. It appears that the COIL is connected to to the threaded stud connection at both ends. The current flowing through the coil (in either direction) will cause a proportional Magnetic field to be generated, causing the pointer to deflect either to the plus or negative direction, depending on the direction of the current flow. It is interesting to note that there are NO values of current flow, just direction. A true ammeter with the corresponding shunt is what I noted in my previous posting (and shown in the video by another contributor). The remaining components shown in your second pix, appears to be a voltage divider network and capacitor, to provide the LED (?) a constant voltage source.
I suggest that you Google the definition and operation of a shunt ammeter to get a better understanding.
Bob Renton

 

[Nacho-RT74]

I know what it is.

Is not an adaptation, is an original Mopar gauge. 77 and lates Chrysler Lebaron/fifth avenue ammeter. ( pic from a FIFTH AVENUE, slightly diff front face but same gauge. The one I have is from the first Lebarons )

this setups got a shunt wire in engine bay side ( check R6*BK shunt around the middle of the pic )

 

[RJRENTON]

Nacho,
Thanks for the email....but...that is not how the instrument operates. I was referring to the instrument in your pix. The instrument shown in the drawing as cavity H and J, is bypsssed by the wire shown as R6BK. IF, this is a shunt, it does NOT measure all the current in the system. If your intention is to measure ALL the current, rather than a percentage of it, fine another should be considered. As i mentioned, the instrument does not have any values as to charge or discharge....without a numeric value what good is it.....its like saying how high is up or why is there air?? This is my opinion.
Bob Renton

 

[Nacho-RT74]

I don't think you are getting it

 

[RJRENTON]

Nacho
I hold a BS in Electrical engineering, a MS in Business Administration and I'm a registered professional electrical engineer, who makes electrical engineering drawings for a living and COMPLETELY understands how a car's electrical system works and the concept of control engineering, with both digital and analog instrumentation.....i really think that perhaps you may not understand what I'm talking about. Why just we leave it go at that?
Bob Renton

 

[Nacho-RT74]

I meant don't think you are getting what I'm telling or asking

I have NOS ammeter from 77/80 Lebaron ( the one pictured ) which must be used with the shunt wire equipped on the car FROM FACTORY. Dunno if you have seen these harnesses with the shunt wire... I have seen it on a 76 Coronet I parted out, long time ago ( maybe 12 years ago or more ? ) when I wasn't aware about these differences between ammeters.

the fact is I never saved this shunt section from the engine harness.

Now, I could wish to become my car on the remote ammeter system with the shunt used on laters cars ( not hard to make ), so would like to know where to find the shunt wire for this conversion IF POSIBLE.

of course I have no idea about the gauge specs or the shunt specs to match this assmebly for the conversion.

The LED indicator is just a plus

I will need just the shunt section and some splices here and there. I still can use the existant ammeter wires on my car which even being 12 gauge, will work the same to feed the milivolts ( I won't need to chnage for 18 or 16 gauge wires ). Of course the splice inside the cab won be on this line, and will be spliced from alt side of the shunt, like factory did.

The diagram I posted is from M body diagram section I have, not a random diagram

maybe the easier will be try to find an Engine harness from any Lebaron/Diplomat and use it as donor... or maybe an Aspen/Volare... or even ANY shunt wire from ANY late Mopar will work ? or maybe the shunt was specific for every car ? dunno if the shunt lenght or thickness changes anything ?

 

[bm02tj]

The way I read this is the factory just measured the voltage drop on the wire and size the wire to accommodate the amperage of the alternator and possible load
So take a know load and 24in wire starting big and working down until you get the reading you need
good luck
PS adjust length to fine tune

 

[383man]

I know we have talked before Nacho and I wish I remembered the size of the shunt Mopar used but its been many years since I had one out of a harness. As we know the only reason for the shunt is to take the load away from the amp gauge and as I have read in my Mopar training it should carry about 90% of the load. I did shorten one years ago and actually made the gauge read a bit more as some of them over the years with the shunt type I found the amp gauge would hardly ever move. Of course that way the customers did not complain like they did with the older setups without shunts as they would show a discharge at night at idle with the lights on and maybe the heater. Customers complained even though all was normal so hence they went to the shunt type. But I shortened the shunt a little at a time until I got the amp gauge to move a little when I turned on the headlites with the eng off. I just cant remember the size of the shunt but I believe the one I messed with was about a 3 ft long 12 gauge wire. Ron